Polarizability converter
Convert molecular polarizabilities between the volume units of chemistry tables, SI and atomic units.
That's about the same as water.
What it means
How polarizable is that?
Static, isotropic (averaged) values. 1 ų = 1.11265 × 10⁻⁴⁰ C·m²/V = 6.748 a₀³.
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That polarizability in every unit
Learn
Three things worth knowing
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× 1.11 × 10⁻⁴⁰
1 ų is 1.113 × 10⁻⁴⁰ C·m²/V; 1 atomic unit (a₀³) is 0.148 ų.
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From the refractive index
Clausius and Mossotti linked a gas’s refractive index to molecular polarizability in the 1850s–1870s, which is how the first values were measured.
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Volume or SI?
Papers that print α = 1.45 mean ų (CGS); in SI the same molecule is 1.6 × 10⁻⁴⁰ C·m²/V. Check the unit before comparing.
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Background
About polarizability
An electric field pulls a molecule’s electrons one way and its nuclei the other, inducing a dipole; polarizability says how large. It governs refractive index, van der Waals forces and Raman spectra.
Tables usually list the polarizability volume in ų, roughly the molecule’s size: helium 0.2 ų, water 1.45, benzene 10.3. The SI value in C·m²/V is 4πε₀ times it.